This article was originally published on The Conversation.
Declines in bee colonies around the world have been widely reported in recent decades. Much attention has been paid to honeybees transporting commercial beekeepers throughout the United States to pollinate crops.
While honeybees are an integral part of our agricultural system, they are widely regarded as the hens of the bee world – domesticated and largely managed for specific agricultural purposes. They are not native to North America and can often not be used as a substitute to understand what happens to native wild bees – the focus of my research.
There are about 5,000 native bee species in North America. Many have shown no signs of decline, and some thrive in heavily urbanized areas. But other species that used to be commonplace are becoming harder to find. As scientists work to understand the decline in bees, it is important to identify the unique roles of indigenous bees and identify the specific threats to them.
Efficient pollinators [1
We need bees for food security and for maintaining healthy ecosystems. Bees pollinate flowering trees and wildflowers, which in turn provide food and habitat for other animals and improve water, air and soil quality.
In addition to honey bees, wild bees are also important for the pollination of crops. Research has shown that the presence of wild bees increases the yields of many types of crops. They are often more efficient at pollinating plants native to North America than honey bees. For example, a honey bee would need to visit a blueberry blossom four times to get the same amount of pollen as a single visit to a bumble bee queen.
Wild bees have a unique opportunity to obtain flower pollen from flowers known as "pollination" "Shaking flowers at a certain frequency releases more pollen, allowing more efficient pollination." Honeybees can not do this. [BumblebeesareespeciallygoodatpollinatingvesiclessosomespeciesarenowcommerciallymanagedandmoreandmorefarmerswhogrowfruitsvegetablesnutsandflowersuseeitherbumblebeesaloneoramixtureofbumblebeesandhoneybeestofeedtheirownPlantspollinate
Bumblebees in distress  But some bumblebee species are in decline.The rusty patched bumble bee ( Bombus affinis ) was once propagated throughout the eastern United States and southeastern Canada but is now only found in a few small populations in the Midwest, and in March 2017 it became the first bee in the lower 48 states, which was listed as an endangered species after an 20-year shrinkage of an estimated 91 percent. Other bumblebees such as the American bumblebee ( B. pensylvanicus ) have declined more slowly.
Reasons for the decline in bumblebee are the increased prevalence of pests and pathogens, the poor diet and the pesticide load. Many of these stressors are due to agricultural intensification, especially in the Midwest. Traditionally, Prairie Meadows provided nutritious dense, safe feed for bees. But most former prairie countries have been converted into corn and soybean fields or developed for commercial and private purposes. As a result, bumblebees are increasingly exposed to pesticides and their food supply is shrinking.
Why do some species thrive while others go back? Some research suggests that traits such as a close or specialized diet and a tall body are associated with a decline. However, much more research is needed to fully understand which features make species susceptible and which species are particularly vulnerable.
In North America there are 46 species of bumblebees; the other native bees (4,954-plus species) vary greatly in size, color, and life history. Since the native bees are so diverse, it is difficult to identify a major reason for the decline of wild bees. But as with bumblebees, poor nutrition and pesticide contamination are likely culprits. We also know that the majority of native bees nest in the soil, so they are vulnerable when natural areas are converted or paved into cultivated agricultural fields. The preservation of safe nesting sites for native bees is therefore crucial for their conservation.
Measurement of Bee Wealth and Biodiversity
I'm part of a team at Michigan State University, which is funded by the US Department of Agriculture's National Institute of Food and Agriculture to close some knowledge gaps about bees. Michigan has 465 documented bee species, each with unique characteristics of life history. It also has a diverse agricultural sector that ranges from specialty crops such as apples, blueberries and sour cherries to large commodity crops such as corn and soybeans. And Michigan habitats range from highly urbanized to untouched wilderness. This diversity helps us to ask questions about how different landscapes affect the local bee community.
To determine how the bees of the state act now, we need to know how rich and diverse communities have been in the past. Fortunately, Michigan has a rich history of surveying bees that goes back several decades. We are now replicating these studies to detect changes in bee colonies.
We also examine bees in different landscapes and regions to identify areas of low bee diversity or variety where conservation efforts may have the greatest impact. But the only way to know if these measures are effective is to track changes in the bee communities in the future. Our project provides an important basis for future comparisons and reviews of conservation programs.
We also monitor the health of managed bumblebees and honey bees that provide pollination services to local plants. One strategy we are testing is whether management practices such as wildflower planting can improve bee health.
The results of this project will provide the hitherto most comprehensive assessment of bees in Michigan. Importantly, we look at all bee species that are managed and wild, as they all play an important role in maintaining a healthy agricultural system and ecosystem.
Kelsey K. Graham, Postdoctoral Researcher, Michigan State University